The mass media play an important role in the nowadays information era. The announcement and promotion of governmental policies, the advertising of business images and products, the live telecast of stage performance, and the display of various information and messages in public places, all can be efficiently and effectively achieved through changeful mass media.
Among others, the electronic signboard is a very effective means to achieve ideal advertising effect. Through control via computers and link to Internet, the effect of the electronic signboard is expanded from local points to worldwide areas. Moreover, the current mass media display not only static graphic designs, but also dynamic images, making the electronic signboard more changeful and flexible to create much enhanced visual effects than other types of advertising media.
An outdoor electronic signboard usually has high brightness and light gathering power to therefore produce a large amount of heat during operation thereof. Moreover, since the outdoor electronic signboard is frequently subjected to sunlight, rainwater, and other weather factors, it must be designed to effectively dissipate heat and prevent water from entering into the signboard.
FIGS. 1 and 2 are perspective and sectioned side views, respectively, of an electronic signboard provided with a first type of conventional heat dissipating structure. The electronic signboard typically includes a main body 10 having a first surface 11 and an opposite second surface 12. The first surface 11 is a display for showing dynamic and/or static visual images. The second surface 12 is provided with a plurality of through holes 121, and a plurality of forward projected shielding covers 122 correspondingly located along an outer edge of the through holes 121. FIG. 1A is an enlarged view showing the shielding cover 122 on one through hole 121.
When the display at the first surface 11 of the main body 10 operates, components of the display in operating produce a high amount of heat, which raises a temperature of the gas inside the main body 10. Therefore, there is a temperature difference between the relatively hot fluid in the main body 10 and the relatively cold external air to cause a natural convection. That is, the hot fluid inside the main body 10 passes through the through holes 121 on the second surface 12 to diffuse into the external environment, so that heat is carried away from the main body 10 to maintain the main body 10 in a pressure balancing state. The projected shielding cover 122 also functions to stop or prevent rainwater and/or other liquid from entering into the main body 10.
However, in the practical application of the above-described first conventional heat dissipating structure for the electronic signboard, while a large part of liquid is stopped by the projected shielding covers 122 from entering into the main body 10 of the signboard, there is still a small part of liquid that flows down along the shielding covers 122 into the main body 10 via the through holes 121 to damage the display at the first surface 11.
FIGS. 3 and 4 are perspective and sectioned side views, respectively, of an electronic signboard provided with a second type of conventional heat dissipating structure. The electronic signboard includes a main body 20 having a first surface 21 and an opposite second surface 22. The first surface 21 is a display for showing dynamic and/or static visual images. The second surface 22 is provided with at least one through hole 221, a forward projected shielding cover 222 correspondingly located along an outer edge of the through hole 221, and a heat dissipating fan 23 mounted in the main body 20 corresponding to the through hole 221. FIG. 4A is an enlarged view showing the shielding cover 222 and the heat dissipating fan 23 at the through hole 221.
When the display at the first surface 21 of the main body 20 operates, components of the display in operating produce a high amount of heat, which raises a temperature of the gas inside the main body 20. The hot fluid inside the main body 20 is discharged by the heat dissipating fan 23 via the through holes 221 on the second surface 22 to diffuse into the external environment, so that heat produced by the display is forced to dissipate from the main body 20. The projected shielding cover 222 also functions to stop or prevent rainwater and/or other liquid from entering into the main body 20.
However, in the practical application of the above-described second conventional heat dissipating structure for the electronic signboard, the provision of the heat dissipating fan 23 would inevitably increase the cost of the electronic signboard, compared to the electronic signboard adopting the first type of conventional heat dissipating structure. Moreover, since the electronic signboard is located outdoors, it is frequently subjected to external environmental factors, such as dust. When the heat dissipating fan 23 rotates to discharge heat, dust in the air tends to adhere to and accumulate on the fan 23 to adversely reduce the heat dissipation efficiency of the fan 23. In a worse condition, the accumulated dust would even shorten the usable life of the fan 23 or cause frequent replacement or repair or maintenance of the fan 23. In addition, as in the first conventional heat dissipating structure, there is still a small part of liquid that would flow down along the shielding cover 222 to invade the main body 20.
It is therefore tried by the inventor to develop a waterproof heat dissipating structure for electronic signboard to eliminate the drawbacks existed in the conventional heat dissipating structure for electronic signboard.